Patent application title: Mixture Based on a Polyisocyanate and a Solvent of Ether Ester Type, Aqueous Emulsion Obtained from this Mixture and Use of this Emulsion for the Manufacture of Coatings and Adhesives

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Mixture Based on a Polyisocyanate and a Solvent of Ether Ester Type, Aqueous Emulsion Obtained from this Mixture and Use of this Emulsion for the Manufacture of Coatings and Adhesives - Patent applicationinit();
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Patent application title: Mixture Based on a Polyisocyanate and a Solvent of Ether Ester Type, Aqueous Emulsion Obtained from this Mixture and Use of this Emulsion for the Manufacture of Coatings and Adhesives

Abstract:

The mixture of the invention comprises at least one cycloaliphatic
polyisocyanate and at least one solvent comprising an ester function and
an ether function. An aqueous emulsion can be obtained from this mixture
which also comprises a compound bearing a function with a mobile
hydrogen, selected from primary or secondary hydroxyl functions, phenol
functions, primary and/or secondary amino functions, carboxylic functions
and a thiol function or a compound containing precursor functions capable
of freeing hydroxyl functions. The emulsion can be used for the
manufacture of coatings on a substrate of cement, of wood or especially
of leather, and also for the manufacture of adhesives.

Claims:

1. A mixture based on polyisocyanate, characterized in that it
comprises:at least one cycloaliphatic polyisocyanate;at least one solvent
comprising an ester function and an ether function; andoptionally a
hydrophilic additive.

2. The mixture according to claim 1, having a viscosity at 5.degree. C.
below 10000 mPas.

3. The mixture according to claim 1 or claim 2, wherein the solvent has a
flash point above 61.degree. C.

4. The mixture according to any one of claims 1 to 3, wherein the solvent
has a boiling point between 50.degree. C. and 350.degree. C.

5. The mixture according to any one of the preceding claims, wherein the
solvent is 3-methoxy-n-butylacetate.

6. The mixture according to claim 1, wherein only 3-methoxy-n-butylacetate
is used as the solvent.

7. The mixture according to claim 1, wherein the proportion of solvent in
the mixture is between 2% and 60%, more particularly between 5% and 50%
and even more particularly between 7% and 40% by mass of solvent in
relation to the whole of the mixture.

9. The mixture according to claim 1, wherein the isocyanurate
polyisocyanate is obtained by catalytic (cyclo)trimerization of
cycloaliphatic diisocyanates.

10. The mixture according to claim 1, comprising in addition one or more
other polyisocyanates, and in particular those which comprise an
isocyanurate of an aliphatic polyisocyanate, in particular hexamethylene
diisocyanate isocyanurate (HDT).

11. The mixture according to any one of claims 1 to 9, wherein the
cycloaliphatic polyisocyanate is IPDT alone.

12. The mixture according to any one of the preceding claims, wherein the
hydrophilic additive is a hydrophilic additive of the non-reactive type.

13. The mixture according claim 1, wherein the hydrophilic additive
corresponds to formula (1) or formula (2): ##STR00003## with, when q is
equal to zero, those of formula (2): ##STR00004## additives of formula
(1) or formula (2) where:p represents zero or an integer between 1 and 2
(closed intervals, i.e. including the bounds);m represents zero or an
integer between 1 and 2 (closed intervals, i.e. including the bounds);the
sum p+m+q is at most equal to three;the sum 1+p+2m+q is equal to three or
five;X and X', similar or different, represent an arm having at least two
carbon groups;n and s, similar or different, represent an integer
selected between 5 and 30, advantageously between 5 and 25, preferably
between 9 and 20 (closed intervals, i.e. including the bounds);
andR1 and R2, identical or different, represent a hydrocarbon
radical, advantageously selected from aryls and alkyls, optionally
substituted, in particular by a halogen atom, especially fluorine.

14. The mixture according to claim 1, comprising:a solvent with ether and
ester function of the alkoxy-alkyl carboxylate type, preferably
3-methoxy-n-butylacetate; anda cycloaliphatic polyisocyanate, preferably
isophorone diisocyanate isocyanurate (IPDT)in proportions of 20% to 50%
by weight of solvent in relation to the total mass of mixture, preferably
25% to 45%, for example 35% by weight of solvent in relation to the total
mass of mixture.

15. An aqueous emulsion comprising a mixture according to claim 1.

16. The aqueous emulsion according to claim 15, characterized in that it
is obtained by emulsification in water of the mixture based on
polyisocyanate, characterized in that it comprises: at least one
cycloaliphatic polyisocyanate; at least one solvent comprising an ester
function and an ether function; and optionally a hydrophilic additive,
said emulsion comprising in addition at least one compound bearing at
least one function with a mobile hydrogen selected from primary or
secondary hydroxyl functions, phenol functions, primary and/or secondary
amino functions, carboxylic functions and a thiol function or a compound
containing precursor functions capable of freeing hydroxyl functions.

17. The aqueous emulsion according to claim 15, characterized in that it
is obtained by emulsification in water of the mixture based on
polyisocyanate, characterized in that it comprises: at least one
cycloaliphatic polyisocyanate; at least one solvent comprising an ester
function and an ether function; and optionally a hydrophilic additive,
said emulsion comprising in addition at least one aqueous dispersion of
polyurethane.

18. The aqueous emulsion according to claim 15, characterized in that it
is obtained by emulsification in water of the mixture based on
polyisocyanate, characterized in that it comprises: at least one
cycloaliphatic polyisocyanate; at least one solvent comprising an ester
function and an ether function; and optionally a hydrophilic additive,
said emulsion comprising in addition at least one aqueous dispersion of
polyurethane and at least one compound bearing at least one function with
a mobile hydrogen selected from primary or secondary hydroxyl functions,
phenol functions, primary and/or secondary amino functions, carboxylic
functions and a thiol function or a compound containing precursor
functions capable of freeing hydroxyl functions.

19. A method for the manufacture of a coating on a substrate,
characterized in that an emulsion according to claim 15 is used.

20. A method according to claim 19, characterized in that the substrate is
a material selected from wood, metals, cements, plastics materials,
textiles and leather.

21. A method according to claim 19, characterized in that the coating is a
coating with adhesive properties.

Description:

[0001]The present invention concerns a mixture based on a polyisocyanate
and a solvent of the ether ester type, an aqueous emulsion obtained from
this mixture and the use of this emulsion for the manufacture of coatings
and adhesives.

[0002]It is known that in the field of paints and varnishes diisocyanates
are widely used, in particular alkylene diisocyanates and their
derivatives of the biuret type or their trimers.

[0003]Until recently, these products were generally used in solution in
organic solvents. However, the use of organic solvents is more and more
often criticized because these solvents, or at least some of them, are
reputed to be toxic or chronotoxic. It is for this reason that endeavours
have been made increasingly to develop techniques which utilize only a
little solvent or which are even devoid of solvent. It is with this aim
that compositions based on polyisocyanate which are both easily
emulsifiable and easily usable in emulsion in water have been perfected.
The water serves in this case as a carrier for the components of the
formulation and make it possible to reduce the organic solvent content
thereof. In addition, such compositions allow the equipment used for
their application to be rinsed with water.

[0004]One of the problems linked to this type of technique is that of
obtaining emulsions which have good stability, i.e. in fact emulsions in
which the size of the particles in suspension in the liquid phase is as
fine as possible. Moreover, it is of course required that the coatings
obtained using these emulsions have, at least overall, properties
comparable with those of the coatings obtained from compositions in
organic solvent. This may be the case in particular with regard to the
appearance, and more particularly the brilliance, water-resistance, or
the speed of drying of the coating.

[0005]The object of the invention is therefore to perfect a polyisocyanate
composition capable of responding to these problems.

[0006]To this end, the invention concerns a mixture based on
polyisocyanate(s), characterized in that it comprises: [0007]at least
one cycloaliphatic polyisocyanate; [0008]at least one solvent comprising
an ester function and an ether function; and [0009]optionally a
hydrophilic additive.

[0010]According to a particular embodiment, the above-mentioned mixture
according to the invention is characterized in that it does not comprise
any compound comprising a thiol function.

[0011]The invention also concerns an aqueous emulsion which is
characterized in that it is obtained by emulsification in water of the
mixture as described above, which mixture comprises at least one
cycloaliphatic polyisocyanate and at least one solvent comprising an
ester function and an ether function, optionally with a hydrophilic
additive, the emulsion additionally comprising at least one compound
bearing at least one function with a mobile hydrogen, selected from
primary or secondary hydroxyl functions, phenols, primary and/or
secondary amino functions, carboxylic functions and a thiol function or a
compound containing precursor functions capable of freeing hydroxyl
functions.

[0012]It has very surprisingly been discovered that, by means of the
mixture according to the present invention used as a hardener for aqueous
coatings, it is possible to obtain coatings resistant to chemical attack,
having increased brilliance and, in addition, to reduce the drying time
of said aqueous coatings.

[0013]Other features, details and advantages of the invention will become
clearer from the following description, and also various specific but
non-limiting examples intended to illustrate it.

[0014]As indicated above, the mixture based on polyisocyanate(s) of the
invention comprises two essential elements: a cycloaliphatic
polyisocyanate and a specific solvent. These two elements will be
described more precisely hereinafter.

[0015]In the present invention, by "cycloaliphatic polyisocyanate" there
is to be understood a polyisocyanate comprising at least one aliphatic
cycle. The compounds particularly preferred are oligomers or
oligocondensates of cycloaliphatic monomers, i.e. in which the skeleton
includes at least one aliphatic cycle; among these products, those which
are particularly preferred are those which come from the homo- or
hetero-trimerization of a cycloaliphatic monomer.

[0023]These monomers are preferably such that at least one isocyanate
function, and advantageously both isocyanate functions, are distant from
the nearest ring by at most one carbon and are preferably connected
directly thereto. In addition, these cycloaliphatic monomers
advantageously have at least one, and preferably two, isocyanate
function(s), selected from the secondary, tertiary or neopentyl
isocyanate functions.

[0024]The best results, in particular in terms of drying time of aqueous
coatings or adhesives in which the hardener comprises a mixture according
to the present invention, are obtained when the conformational freedom of
the cycloaliphatic monomer is low. As monomers capable of giving good
results, it is possible to cite by way of example, and even paradigm, the
following monomers: [0025]compounds corresponding to the hydrogenation
of the aromatic nucleus or nuclei bearing isocyanate functions of
monomers of aromatic isocyanates and in particular of TDI (toluene
diisocyanate) and diisocyanato-biphenyls, the compound known under the
letter symbol H12MDI (4,4'-dicyclohexylmethanediyl diisocyanate) and
the various BICs [bis(isocyanato-methylcyclohexane)]; [0026]and
especially [0027]norbornane diisocyanate (or
2,5(6)-diisocyanato-methylbicyclo[2,2,1]heptane) often called by its
letter symbol NBDI; and [0028]isophoronediisocyanate or IPDI or
1-isocyanato-3,3,5-trimethyl-5-diisocyanatomethylcyclohexane.

[0029]Advantageously, the cycloaliphatic polyisocyanate of the invention
is an isocyanurate polyisocyanate obtained from cycloaliphatic
diisocyanates, preferably IPDT, NBDT, H12MDT or 1,3-BDT (1,3-BIC
trimer). The isocyanurate polyisocyanate is preferably obtained by
catalytic (cyclo)trimerization of cycloaliphatic diisocyanates.

[0030]According to a particular embodiment of the invention, the
cycloaliphatic polyisocyanate is the product of homocondensation of
isocyanate IPDI or comes from a mixture of the products of
homocondensation, of addition, of the isocyanates HDI and IPDI.

[0031]Preferably, the cycloaliphatic polyisocyanate is the product of
homocondensation of the isocyanate IPDI alone, which is preferably
cyclotrimerized into isocyanurate of IPDI, referred to hereinafter as
IPDT.

[0032]One, two or more other polyisocyanates may form part of the mixture
according to the present invention. The polyisocyanate(s) may be selected
from any polyisocyanate known in the field, and in particular from the
products of homocondensation or heterocondensation of
alkylenediisocyanates, comprising in particular products of the "biuret"
type and of the "(cyclo)trimer" type, even "prepolymers" with isocyanate
function, optionally including urea, urethane, allophanate, and/or ester
amide functions, and from mixtures containing them.

[0033]They may, for example, be polyisocyanates marketed by the company
Rhodia, under the name "Tolonate®".

[0051]As other monomers, it is also possible to cite the aromatic
monomers, such as, for example, 2,4-toluene diisocyanate (TDI),
2,6,4,4'-diphenylmethane diisocyanate (MDI), 1,5-naphthalene diisocyanate
(NDI), tolidine diisocyanate (TODI) and para-phenylene diisocyanate
(PPDI), as well as the monomers corresponding to the hydrogenation
products of the aforementioned aromatic monomers.

[0052]As indicated previously, the other essential element of the mixture
based on polyisocyanate of the invention is the solvent. The aliphatic
polyisocyanates used in the mixture of the present invention, and in
particular when they comprise polyisocyanurate-type derivatives of
cycloaliphatic diisocyanate, are as a general rule products with high
viscosity at ambient temperature, and may even be in the form of vitreous
and amorphous solids which it is necessary to "dilute", or even
"dissolve" in the organic phase in order to be able to utilize them.

[0053]This dilution may be obtained by means of solvents which must be
judiciously selected according to their physico-chemical character, their
solvent power, and also their effect on the properties in the
applications in the aqueous phase. In particular, the solvent should be
sufficiently hydrophobic to "solubilize" (or "dilute") the cycloaliphatic
polyisocyanate, but must also be compatible with the aqueous emulsions
for which the mixture of the invention is intended.

[0054]In addition, among the important criteria for the selection of a
solvent suitable for applications in the aqueous phase may be cited the
characteristics of non-inflammability and of absence of odour or low
odour of said solvent. For the solvents conventionally used in the
systems for coatings and adhesives in the solvent phase have unacceptable
characteristics of inflammability and of unsuitable odour in the aqueous
phase.

[0055]The research which has led to the present invention has made it
possible to determine that the solvents comprising both an ester function
and an ether function may fulfil the various requirements mentioned
above.

[0056]Advantageously, the solvent used in the mixture of the invention is
selected from the following solvents: 1-methoxy-2-propylacetate,
3-methoxy-n-butylacetate, diethylene glycol butyl ether acetate,
butylethylene glycol acetate and ethyl ethoxyproprionate.

[0057]Preferably, the solvent is 3-methoxy-n-butylacetate.

[0058]In addition, the solvent(s) used in the mixture of the invention
has/have the advantage of imparting to said mixture a suitable viscosity
according to the type of application desired. In particular, it was
observed that the mixtures according to the invention have viscosities at
5° C. of less than 10000 mPas, even for mixtures including a
relatively small quantity of solvent, of the order of 35% by weight in
relation to the total mass of the mixture.

[0059]Thus, the solvent(s) used in the mixture of the present invention
allow(s) easy utilisation with a polyisocyanate, at a low temperature,
and with a small quantity of solvent(s) used, compared with the solvents
customarily used in the paint field, such as, for example, solvents of
the butyl acetate type and others.

[0060]Moreover, the advantages of the solvent of the invention are in
particular its low odour and its non-inflammability. The term
"non-inflammability" means that the flash point of the solvent is above
61° C., measured according to standard DIN 517-55. Thus, for
example, 3-methoxy-n-butylacetate has a flash point of 62° C.

[0061]The invention of course covers the case where the mixture contains a
plurality of solvents. The solvents may be a mixture of solvents
according to the invention. This may also be a combination of a solvent
or of a mixture of solvents according to the invention with one or more
other known solvents used for this type of mixture, for example butyl
acetate, esters of carboxylic acid, such as propylene carbonate, lactones
such as ε-caprolactone, and N-ethylpyrrolidone. However, the
solvents will preferably be selected from those which are
non-inflammable, non-toxic (to man and the environment) and have a low
odour (for reasons of nuisance and unpleasantness for the operators
during application).

[0062]A solvent is preferably used which has a boiling point between
50° C. and 350° C., more particularly between 100°
C. and 300° C. For solvents having a boiling point above
300° C., or even 350° C., result in coatings and adhesives
in which the drying time will be very, or even, too long for the
applications envisaged.

[0063]The proportion of solvent in the mixture of the invention is
generally between 2% and 60%, more particularly between 5% and 50% and
even more particularly between 7% and 40% by mass of solvent in relation
to the whole of the mixture.

[0064]It will be noted that in the case of a mixture of one or more
solvents according to the invention with one or more of the known
solvents mentioned above, the proportion of solvent according to the
invention is preferably at least 30% by mass in relation to the whole of
the solvents, the overall proportion in the whole of the solvents then
remaining within the range given in the previous paragraph.

[0065]The mixture of the invention is advantageously "emulsifiable in
water". By a mixture "emulsifiable in water" there is to be understood a
mixture which, when it is placed in water, is capable of providing an
emulsion, i.e. a liquid medium formed of particles (droplets) of liquid
dispersed in another liquid phase.

[0066]Preferably, the mixture is of the self-emulsifiable type, i.e., it
is a mixture capable, in the presence of a liquid medium in which said
mixture is immiscible, of forming an emulsion by a spontaneous mechanism.
In the spontaneous emulsification mechanism, the energy required to form
an emulsion concerns solely the energy required to redistribute the
substance to be emulsified in the mixture: thus there is no need for
external energy, fundamentally agitation energy, in order to create the
emulsion. In other words, simple manual agitation suffices to effect
macroscopically uniform distribution of the discontinuous phase and thus
to obtain the emulsion.

[0067]So that the mixture of the invention is emulsifiable within the
meaning given above, it generally additionally includes an additive
allowing it to be emulsified in water, or to render it hydrodispersable
or hydrosoluble. The additive is generally a hydrophilic additive, of the
surfactant type, and it includes in its structure at least one
hydrophilic function. In the continuation of the description, the term
"hydrophilic additive" will be used.

[0068]A number of variants may therefore be envisaged.

[0069]According to a first variant, the mixture contains a hydrophilic
additive of the non-reactive type, i.e. the additive is present in
admixture with the mixture of the invention without there having been a
reaction between the additive and the polyisocyanate of the mixture.

[0070]In this first variant, the additive may nevertheless react in an
undesirable manner with the other components present in the mixture. The
hydrophilic additive is, however, considered to be in a substantially
free form in the mixture of the invention. In this context, the
expression "substantially free form" means that less than 30%, and
advantageously less than 20%, preferably less than 10%, even more
preferably less than 5%, or even less than 2% by mass of the hydrophilic
additive is in the bonded form, although it has been incorporated in the
form of a mixture, without wishing to cause it to react with the other
component(s) of the mixture.

[0071]As the non-reactive hydrophilic additive, there may be mentioned
those described in the documents WO 97/31960 and FR 2855768-A1, the
teaching of which may be referred to. These additives have an anionic
function and advantageously a fragment of polyethylene glycol chain of at
least one, and preferably of at least 5 ethylenyloxyl units.

[0072]Among these additives, more particular mention may be made of the
those of formula (1) below:

##STR00001##

with, when q is equal to zero, those of formula (2):

##STR00002##

additives of formula (1) or formula (2) where: [0073]p represents zero
or an integer between 1 and 2 (closed intervals, i.e. including the
bounds); [0074]m represents zero or an integer between 1 and 2 (closed
intervals, i.e. including the bounds); [0075]the sum p+m+q is at most
equal to three; [0076]the sum 1+p+2m+q is equal to three or five; [0077]X
and X', similar or different, represent an arm having at least two carbon
groups; [0078]n and s, similar or different, represent an integer
selected between 5 and 30, advantageously between 5 and 25, preferably
between 9 and 20 (closed intervals, i.e. including the bounds); and
[0079]R1 and R2, identical or different, represent a
hydrocarbon radical, advantageously selected from aryls and alkyls,
optionally substituted, in particular by a halogen atom, especially
fluorine.

[0080]The counter-cation is advantageously monovalent and is selected from
inorganic cations and organic cations which are advantageously
non-nucleophilic and of a quaternary or tertiary nature, in particular
the "oniums" of column V such as phosphonium, ammonium, or of column VI
such as sulphonium, and mixtures thereof. Counter-cations of the ammonium
type, coming from an amine, advantageously of the tertiary kind, are
preferred. It is also preferred to avoid the organic cation having a
hydrogen reactive with the isocyanate function. The periodic
classification of the elements used in the present application is that of
the supplement to the Bulletin of the French Chemical Society (Bulletin
de la Societe Chimique de France), January 1966, No. 1.

[0081]Thus, particularly preferred non-reactive hydrophilic additives are
the additives known under the name "Rhodafac®" of the company Rhodia
which are generally used in their neutralized form, said neutralization
being able to be carried out before or during, preferably before, the
addition of the additive to the mixture. Neutralization may in particular
be effected by means of amines, as indicated above, in particular by
dimethylcyclohexylamine or DMCHA.

[0082]According to a second variant, the mixture contains a hydrophilic
additive of the reactive type, i.e. the additive is present in the
mixture but being grafted onto the polyisocyanate of the mixture. As
additives that can be grafted onto polyisocyanates, it is possible to
cite the hydrophilic additives mentioned in U.S. Pat. No. 4,663,377, the
teaching of which may be referred to.

[0083]As other graftable additives it is also possible to cite those of
the non-ionic or ionic (cationic or anionic) type such as those mentioned
in EP-A-0703255 (the teaching of which may be referred to), additives
comprising --SO3H or --SO3-- groups. The additives grafted onto
the polyisocyanate of the mixture according to the present invention are
not however preferred.

[0084]Finally, according to a third variant, it is possible to combine the
two preceding variants, i.e. the mixture contains both a non-reactive
hydrophilic additive and a grafted hydrophilic additive.

[0085]The mass ratio between the polyisocyanate(s) of the mixture and the
hydrophilic additive is most often at most equal to around 33%, and
advantageously at most equal to around 20%, preferably to around 12%.
This mass ratio is advantageously greater than 1%, preferably than 2%.

[0086]The hydrophilic additive may be introduced into a mixture comprising
the cycloaliphatic polyisocyanate(s) and the solvent of the invention.
The hydrophilic additive may be added by simply mixing the additive with
the cycloaliphatic polyisocyanate(s) in solution in the solvent.

[0087]In the case of a hydrophilic additive of the reactive type, mixing
may take place more particularly at a temperature between, for example,
50° C. and 130° C., according to the type of additive.

[0088]On the other hand, in the case of a hydrophilic additive of the
non-reactive type, in particular for phosphate-based hydrophilic
additives, mixing should not be carried out at too high a temperature,
and is generally carried out at a temperature varying from 10° C.
to less than 100° C., preferably at a temperature of between
10° C. and 90° C., and more preferably between 10°
C. and 80° C., for example at around 50° C.

[0089]In this regard, it is desirable to incorporate the non-reactive
hydrophilic additive in a mixture which is the least viscous possible,
which is made possible by means of the solvent described above.

[0090]Quite particularly preferred are the mixtures of the invention which
comprise: [0091]a solvent with ether and ester function of the
alkoxy-alkyl carboxylate type, preferably 3-methoxy-n-butylacetate; and
[0092]a cycloaliphatic polyisocyanate, preferably isophorone diisocyanate
isocyanurate (IPDT),in proportions of 20% to 50% by weight of solvent in
relation to the total mass of mixture, preferably 25% to 45%, for example
35% by weight of solvent in relation to the total mass of mixture.

[0093]According to one variant, quite particularly preferred are the
mixtures of the invention which consist of a mixture of: [0094]a
solvent with ether and ester function of the alkoxy-alkyl carboxylate
type, preferably 3-methoxy-n-butylacetate; and [0095]a cycloaliphatic
polyisocyanate, preferably isophorone diisocyanate isocyanurate (IPDT)in
proportions of 20% to 50% by weight of solvent in relation to the total
mass of mixture, preferably 25% to 45%, for example 35% by weight of
solvent in relation to the total mass of mixture.

[0100]in proportions of 20% to 50% by weight of solvent in relation to the
total mass of mixture, preferably 25% to 45%, for example 35% by weight
of solvent in relation to the total mass of mixture, and with a mass
ratio between the hydrophilic additive and the polyisocyanate(s) of the
mixture equal at most to around 33%, advantageously equal at most to
around 20%, preferably around 10%, and advantageously greater than 1%,
preferably than 2%.

[0101]Among the mixtures which have just been defined, said mixtures are
also preferred which comprise in addition one or more other
polyisocyanates, and in particular those which comprise an isocyanurate
of an aliphatic polyisocyanate, in particular hexamethylene diisocyanate
isocyanurate (HDT).

[0102]The mixture of the present invention may in addition contain one or
more organic or inorganic additives, such as those commonly used in the
field, and for example selected from stabilizers, antioxidants, pigments,
rheological additives, thickeners, surfactants, and catalysts, according
to the properties desired.

[0103]The mixture according to the present invention is thus generally,
and most often, in the form of a homogeneous and slightly viscous liquid,
in particular having a viscosity below 10000 mPas at a temperature of
5° C., and in particular below 2000 mPas at 25° C. (for a
solvent content of 35% by weight).

[0104]The mixture of the invention may be utilized with one or more
aqueous dispersions of polyurethane. Aqueous dispersions suitable within
the scope of the invention are known per se and are described, for
example, in the documents U.S. Pat. No. 3,479,310, GB 1076688, U.S. Pat.
No. 4,108,814, U.S. Pat. No. 4,092,286, DE 2651505, U.S. Pat. No.
4,190,566, DE 2732131, DE 2811148, or in the documents US 2006/240264, US
2005/288431, US 2005/209425, U.S. Pat. No. 7,012,115 or EP 986592.

[0105]As seen above, the invention also concerns an aqueous emulsion
obtained starting from the mixture comprising a cycloaliphatic
polyisocyanate and the solvent, such as were described previously.

[0106]The aqueous phase of the emulsion serves as a vector of the
co-reagents polycondensable with the polyisocyanate(s) of the mixture,
i.e. the compound or compounds with a mobile hydrogen mentioned
previously.

[0107]The compounds with a mobile hydrogen that are usable are well known.
Preferably, these compounds are selected from polyalcohols which can be
used alone or in admixture or compounds containing precursor functions
capable of freeing hydroxyl functions. These may advantageously be
acrylic polymers, polyesters, polyurethanes or hybrids of these polymers.
Polyethers may also be mentioned.

[0108]As precursor functions capable of freeing hydroxyl functions, it is
possible to cite, for example, epoxy functions, carbonate functions or
dioxolane functions. These precursor functions free the hydroxy functions
by reaction with a suitable nucleophile such as an amine or water,
optionally in the presence of a catalyst which may be an acid compound or
a Lewis acid in an amount by weight which may be between, for example, 50
ppm and 5000 ppm, more particularly between 100 ppm and 500 ppm, an
amount expressed by weight of catalyst in relation to the dry extract of
the polyisocyanate composition and of the compound bearing at least one
function with a mobile hydrogen.

[0109]The emulsion may of course include one or more (i.e. a mixture of)
compounds with mobile hydrogen, with, if necessary and if it is desired
for the applications envisaged, one or more aqueous dispersions of
polyurethane described above.

[0110]The emulsion may in addition contain one or more organic or
inorganic additives, such as those commonly used in the field, and for
example selected from stabilizers, antioxidants, pigments, rheological
additives, thickeners, surface agents and catalysts, according to the
properties desired.

[0111]The invention also concerns a method for the manufacture of a
coating on a substrate in which the emulsion described above is used. By
coating, there is to be understood any type of layer applied as a whole
or in part on a substrate of a nature to protect and/or to decorate it,
for example a paint or a varnish.

[0112]The method is employed by applying the emulsion to the substrate by
any known technique. The substrate is a material which may be selected
from wood, metals, cements, plastics materials, textiles and leather.

[0113]In the case of a metallic substrate, the metal may for example be
aluminium or a steel.

[0114]It will be noted that the method applies to substrates which may
have a plurality of superposed coatings and, in this case, the product of
the invention may be used for the preparation of any one of these
coatings. However, the product of the invention may advantageously be
used for a finishing coating, and this is the case in particular for
leather substrates.

[0115]Once the emulsion is deposited, the reaction between the
polyisocyanate of the mixture and the compound bearing at least one
function with a mobile hydrogen may take place at ambient temperature or
in heat at a temperature which may be between 30° C. and
300° C., preferably between 40° C. and 250° C. and
even more preferably between 50° C. and 150° C., preferably
below 100° C. The temperature and crosslinking time are adapted
according to the substrate. In the case of substrates sensitive to
temperature, crosslinking catalysts will be used more particularly.

[0116]The coatings obtained, which comprise the mixture according to the
present invention, have an increased degree of brilliance, and also a
suitable drying time, which degree of brilliance and drying time are at
least comparable with, or even better than, the coatings known in this
field. The coatings comprising the mixture of the present invention have
proved in particular to be more brilliant than similar coatings where the
solvent used is a solvent of the ester type, in particular of the
carbonate type.

[0117]The emulsion of the invention may also be used as an adhesive. In
such a case, a coating is formed as described above, the coating here
having adhesive properties, on a substrate intended to be adhesively
secured to another element. The substrate may quite particularly be a
substrate made of wood.

[0118]Examples will now be given by way of illustration without imparting
any limitation to the invention which is defined by the claims appended
to the present description.

[0119]The term "viscosity" employed in the present description, the
examples which follow and the appended claims, is to be understood as
dynamic viscosity. The measurement of viscosity is based on the principle
of a cylinder rotating in the sample to be studied placed in a coaxial
tank. The torque required to overcome the resistance offered by the
product to the rotation of a cylinder is measured.

[0120]The equipment used is a Rheovisco 2 M apparatus of the company RHEO,
equipped with a thermostatically controlled LAUDA bath and with an
EIRELEC MT100 KC temperature probe.

[0121]The viscosity (in centipoise (cP) or in mPas) is read directly on
the display screen. The accuracy of measurement is ±1.5% of the full
scale value.

[0122]By way of example, the viscosity of a product at 200 cP is measured
by means of the DIN 24 geometry at 60 r.p.m. At this speed, the full
scale viscosity is 239.2 cP, or an accuracy of 239.2×1.5%=4 cP. The
viscosity of a product at 4000 cP is measured by means of the DIN 14
geometry at 12 r.p.m. At this speed, the full scale viscosity is 6006.6
cP, or an accuracy of 6006.6×1.5%=90 cP.

EXAMPLES

Example 1

Dissolution of IPDI Isocyanurate (IPDT)

[0123]a) Standard Mode of Operation

[0124]The following standard mode of operation was used to effect the
dissolution of solid (powder) IPDT (CAS RN: 53880-05-0) in the following
different solvents:

[0128]The whole of the solvent is fed in and heating is carried out at
around 50° C. One third of the mass of IPDT is rapidly added. The
temperature rate is raised to 90-130° C., according to the
solvents, for example 90° C. for methoxy-n-butylacetate.

[0129]The remainder of the IPDT is then added and agitation is continued
for 1 to 2 hours, according to the solvents.

[0131]180 g of a mixture of IPDT/methoxy-n-butylacetate at 65% dry extract
(i.e. 65% by weight of IPDT; 35% by weight of methoxy-n-butylacetate) are
prepared, starting from 117 g of solid IPDT (Huls Corporation; of
Vestanate® T 1890/100 type; presentation in the form of granules
having a diameter of less than 0.8 cm) and 63 g of methoxy-n-butylacetate
solvent (Societe Celanese).

[0132]The whole of the solvent (63 g) is placed in a 300 ml reactor
previously cleaned with the reaction solvent and dried by flushing with
nitrogen.

[0133]The reactor is then heated to 50° C. and around one third of
the total amount (39 g) of solid IPDT is added while agitating
mechanically.

[0134]After 15 minutes' agitation, the reactor is heated to 90° C.,
at which temperature the remainder of the solid IPDT (78 g) is added over
30 minutes while agitating.

[0135]Agitation is continued at a temperature of 90° C. for 1 hour.
The mixture is then filtered while hot (mesh size 30 μm), at a
temperature of around 40° C.

Example 2

Viscosity Test

[0136]With butyl acetate used as dissolvent of the IPDT according to the
above mode of operation, a viscosity of less than 1000 mPas may be
obtained. However, this solvent has a low flash point (22° C.) and
an aggressive odour which is a nuisance for certain applications.

[0137]The use of Highsolv® with a higher flash point (59° C.)
leads to a significant increase in the viscosity (1890 mPas at 25°
C.).

[0138]On the other hand, the solutions of IPDT in methoxy-n-butylacetate
(flash point: 62° C.) (Example 1.b) above), themselves impart to
the mixture a low viscosity (760 mPas at 25° C.), even at a low
temperature, while keeping the odour acceptable. Thus less than 7 000
mPas is measured at 5° C., at which temperature a solution in
Highsolv® of the same titre of IPDT no longer flows.

Example 3

Test for Ease of Dissolving and Handling

[0139]Another advantage provided by solvents of the ether ester type, such
as, for example, methoxy-n-butylacetate, is the ease of dissolution.
Generally it is sufficient to heat the solvent/solid IPDT mixture at a
temperature below 100° C., for example around 90° C., for
around 2 hours in order to obtain a homogeneous mixture of stable
viscosity. It is even possible to obtain the mixture by agitating at
ambient temperature for one night.

[0140]In order to produce the same mixture with Highsolv® P it is
necessary to heat beyond 90° C., thus modifying both the viscosity
and the colour of the solution.

[0141]In addition, when they are exposed to temperatures below 15°
C., the solutions in Highsolv® P become difficult to pump
(viscosity>10000 mPas). The mixture of IPDT/methoxy-n-butylacetate
(65% and 35% by weight respectively) reaches this limit only towards
0° C.

Example 4

Preparation of a Self-Emulsifiable Composition

[0142]Into a 300 ml reactor, previously cleaned with the reaction solvent
and dried by flushing with nitrogen, are placed 143 g of hexamethylene
diisocyanate isocyanurate (HDT with theoretical NCO titre 22.0±0.5;
Company Rhodia).

[0144]There are then added, by means of a "push syringe", over 30 to 45
minutes, while continuing agitation, 13.8 g of non-reactive hydrophilic
additive of the ethoxylated phosphate ester type (Rhodafac® range,
supplier: Rhodia), characterized by a hydrophobic head at C13, an
average ethoxylated chain length of 7 ethylene oxide units and an average
acidity value of 185 mg KOH/g.

[0145]During this stage, the temperature of the reactor is kept below
50° C. by cooling.

[0157]This mixture is then added to various solvents, in the amounts
indicated (in grams) in the following table, in order to obtain the
compositions described as part B (compositions B1 to B4) of the
formulations of examples 6 to 9 respectively:

[0158]In addition there is used, as part B5 (by way of comparative
example), Rhodocoat® X EZ-D 401 (Company Rhodia), a self-emulsifiable
mixture based on IPDT and hydrophilic additive, in butyl acetate.

[0159]The compositions B1 to B5 are then mixed manually with a part A
(reference Flow® gloss of BONA), commercial, intended for the
application of coatings to parquet.

[0160]The ratio used is 10 parts of A to one part of each of the B parts
(B1 to B5).

[0161]The formulations A+B are then applied to glass plate and the
following measurements are carried out:

[0162]Duration of Incorporation

[0163]The time required (expressed in minutes) to obtain a homogeneous
mixture of A+B is measured.

[0164]Drying Time

[0165]T1 is characterized by the "dust-dry" drying time. After application
of the film, T1 corresponds to the time (expressed in minutes) starting
from which small balls of glass may be removed by light brushing without
damaging the surface.

[0166]Determination of Return to Hardness

[0167]This technique consists in following the development of the Persoz
hardness of a film of varnish or paint during drying (after 1 day (D1),
three days (D3) and seven days (D7)) by means of a type 300 Erichsen test
pendulum. The principle of the Persoz hardness pendulum is based on the
fact that the oscillations of a pendulum placed on a sample are damped
more, the softer the layer of varnish. It consists in measuring the
hardness of a film by the damping of the oscillations of a pendulum from
12° to 4° which rests on the film by means of two steel
balls of the same diameter. The results are expressed in seconds. The
more or less rapid development of the Persoz hardness over time makes it
possible to follow the construction of the network.

[0168]Brilliance

[0169]The brilliance of a coating is one of the most usefully measurable
properties. The principle is to direct a luminous beam, at an angle of
20°, 60° or 85°, onto the surface to be examined.
The rays reflected are collected by a photoelectric cell. By means of a
galvanometer, the apparatus gives a value from 0 to 100 proportional to
the brilliance. A ceramic standard serves as reference and represents the
maximum value. The brilliance is expressed in % (or unit of brilliance).

[0170]The formulations based on the use of IPDT prepared in a solvent
including an ester function and an ether function, such as methoxybutyl
acetate, have shorter mixing times, in comparison with a composition of
IPDT in butyl acetate (comparative example 10). In addition, the
brilliance obtained is also greater, the sign of a better compatibility
of parts A and B.

[0171]Example 7 in particular exhibits a good compromise between dust-dry
drying time, brilliance and development of hardness.

[0174]The mixture A+B is then produced with manual agitation and the
viscosity of the formulation is adjusted, by the addition of water, to a
viscosity of 22 s. measured by DIN 4 cup at 23° C. The pot life of
the formulation is then measured.

[0175]The measurement of the brilliance and of the Haze over time is used
to evaluate this pot life.

[0176]The level of brilliance and of Haze are excellent for both
formulations in the initial state.

[0177]However, for Example 11 based on the mixture according to the
invention, a more moderate reduction in brilliance and increase in the
Haze are noted, thereby indicating an improved stability of the
composition.

[0178]The mechanical properties of the coating are also measured after
application to a metal plate and drying in controlled conditions
(23° C., 50% relative humidity) for 7 days.

[0179]Falling Ball Test for Resistance to Impact

[0180]This involves evaluating the impact-resistance of a film of paint or
varnish on a steel plate by observing the appearance of crazing or
peeling.

[0181]The test consists in subjecting the coating to the impact of a
striking pin of specific dimensions and weight, the drop height of which
is adjustable. The maximum height at which the film of paint is no longer
damaged by the impact is thus determined.

[0182]Two (Erichsen) falling ball test apparatuses are available, one
equipped for AFNOR impacts (weight of 1000 g) and the other for ASTM
impacts (weight of 910.3 g).

[0183]The result given indicates the maximum height obtained before the
appearance of crazing:

[0187]The chemical resistance in relation to numerous aggressive agents is
evaluated. The film is exposed to cotton soaked with various aggressive
agents. After a certain time, visual assessment of the film is carried
out, giving 0 to 5 or 6 according to the aggressive agents (0=film
intact, 5 or 6=film destroyed).

[0188]Example 13 shows a resistance to chemical attack greater for the
coating comprising the mixture according to the invention.

[0189]The present invention, therefore, is well adapted to carry out the
objects and attain the ends and advantages mentioned, as well as others
inherent therein. While the invention has been depicted and described and
is defined by reference to particular preferred embodiments of the
invention, such references do not imply a limitation on the invention,
and no such limitation is to be inferred. The invention is capable of
considerable modification, alteration and equivalents in form and
function, as will occur to those ordinarily skilled in the pertinent
arts. The depicted and described preferred embodiments of the invention
are exemplary only and are not exhaustive of the scope of the invention.
Consequently, the invention is intended to be limited only by the spirit
and scope of the appended claims, giving full cognizance to equivalents
in all respects.